Nitrogen amines

Compounds with a high HOMO and LUMO (Figure 5.5c) tend to be stable to selfreaction but are chemically reactive as Lewis bases and nucleophiles. The higher the HOMO, the more reactive. Carbanions, with HOMO near a, are the most powerful bases and nucleophiles, followed by amides and alkoxides. The neutral nitrogen (amines, heteroaromatics) and oxygen bases (water, alcohols, ethers, and carbonyls) will only react with relatively strong Lewis acids. Extensive tabulations of gas-phase basicities or proton affinities (i.e., —AG° of protonation) exist [109, 110]. These will be discussed in subsequent chapters. 

Amines and amides are two classes of organic compounds which contain nitrogen. Amines behave as organic bases and may be considered as derivatives of ammonia. Amides are compounds which have a carbonyl group connected to a nitrogen atom and are neutral. In this experiment, you will learn about the physical and chemical properties of some members of the amine and amide families. 

If the hydrogens of ammonia are replaced by alkyl or aryl groups, amines result. Depending on the number of carbon atoms bonded directly to nitrogen, amines are classified as either primary (one carbon atom), secondary (two carbon atoms), or tertiary (three carbon atoms) (Table 33.1). 

Amidines, N-(l,2,4-thiadiazol-5-yl)-, rearrangement, 56, 103 Amidoximes, 1,2,4-oxadiazol-3-yl-, rearrangements, 56, 55 Amidyl radicals, see Radicals, nitrogen Amination, asymmetric, of carboxylic acids by chiral nitroso compds, 57, 41 Amines, catalysis of 3-acyl-1,2,4-oxadiazole arylhydrazone rearrangement by, 56, 87 Amines, thionitroso-, formation, 55, 20 Aminium cation radicals, see Radicals, nitrogen... 

Vitamins are vital (= vita) and mainly nitrogenous (= amines) substances of low-molecular weight. As a rule, they must be present in the diet as essential components. Only a few vitamins (e.g. A, K, Bi, B5, B12, folic acid, biotin) are formed in the intestine by bacteria. Plants constitute the main source of exogenous vitamin supply. In a biochemical context, the principal bio-catalytic effect of vitamins consists in substituting cofactors of enzymes which have undergone metabolic degradation. 

Another class of organic compounds contains nitrogen. Amines contain nitrogen atoms bonded to carbon atoms in afiphafic chains or aromatic rings and have the general formula RNH2. 

In 1912, Cashmir Funk isolated thiamine from rice husks and coined the term vitamine because they were required for life ( vita ) and because thiamine contained nitrogen ( amine ). The original term vita-mine was changed to vitamin when scientists identified and purified all the vitamins and discovered that they did not all contain the element nitrogen. 

Strong cation-exchange sorbent. This approach would be used for organic cations and combined with a methanol eluate (50 50 methanol/water) to help prevent sorption to the matrix of the sorbent by van der Waals interactions and to assist elution. Also the pH can be adjusted in the elution solvent such that the organic cation will loose its charge that is, the pH should be two pH units above the pA. Sodium hydroxide or potassium hydroxide may be used here to raise the pH in combination with the methanol (0.1 A). Organic compounds that contain nitrogen (amines) work well by this mechanism. 

The potential tautomerism of the cyclic ones vs. ols , imines vs. amines , and thiones vs. thiols is recognized and, for the sake of uniformity, the respective structures with oxygen are named ones , with nitrogen amines , and with sulfur thiols or sulfanyl derivatives, wherever suitable. 

Because of the lone pair on the nitrogen, amines are both bases and nucleophiles. Amines react as nucleophiles in nucleophilic substitution reactions, in nucleophilic acyl substitution reactions, in nucleophilic addition-elimination reactions, and in conjugate addition reactions. 

Simple organic nitrogen (Amines, amino acids, etc.)... 

Carbamates are characterized by a O—CO—N group, which has an electron withdrawing ester unit on the nitrogen. Amines are easily converted to carbamates (sec. 7.3.C.iii) and reduction usually proceeds with... 

The most important reaction of platinum(II) alkene complexes is nucleophilic attack at a coordinated carbon atom. The most studied nucleophile in this context is the amine nitrogen. Amines attack coordinated monoalkenes, and if tertiary phosphine or amine ligands are present these stabilize the Zwitterionic platinum-carbon a-bonded complexes that are formed (equation 239) The attack occurs trans to platinum. Substituents adjacent to the... 

Nitrogen.—Amines, Enamines, Imines, Oximes, Isocyanates, Cyanides, and Related Compounds. Perfluorotributylamine, (C4F9)sN (FCM3 ), has continued to feature in work on medical applications (blood oxygenation etc.) of fluorocarbon-type... 

The strength of the base increases with the number of alkyl groups attached to nitrogen. Amines can be prepared from ammonia and an alkyl halide ... 

Since the d orbitals are believed to be unavailable in nitrogen, amine oxides, RjN- O do not form double bonds and are markedly less stable than phosphoryl compounds. 

Wick CD, Stubbs JM, Rai N et al (2005) Transferable potentials for phase equilibria. 7. United-atom description for nitrogen, amines, amides, nitriles, pyridine and pyrimidine. J Phys Chem B 109 18974-18982... 

Nitrogen.—Amines, Imines, Cyanides, Isocyanides, and Isocyanates. Information relating to the application of FC-43 [(C4F,)aN] and other fluorocarbon-type liquids as oxygen-transport agents in artificial blood continues to mount. °° The advances made are also being reported in the popular... 

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